#include <stdio.h>
int sum(int,int);
int product(int,int);
int difference(int,int);
int any_function(int(*pfun) (int,int),int x,int y);
int main(void){
  int a = 10;
  int b = 5;
  int result = 0;
  int (*pf)(int ,int)=sum;//int *pf (int ,int)=sum;也行
  
  result=any_function(pf,a,b);
  
  printf("result = %2d\n",result);
  
  result=any_function(product,a,b);
  printf("result = %2d\n",result);
  printf("result = %2d\n",any_function(difference,a,b));
  
return 0;
}
int any_function(int(*pfun)(int,int),int x,int y){
  return pfun(x,y);
}
int sum(int x,int y){
  return x+y;
}

int product(int x,int y){
  return x*y;
}

int difference(int x,int y){
  return x-y;
}
